DuckDB has a flatten() function that we can use to flatten nested lists. The function concatenates a list of lists into a single list. So whether the outer list contains just one list or multiple lists, we can use the flatten() function to flatten them into one list.
However, it only goes one level deep, so that’s something to keep in mind.
Continue readingDuckDB provides us with a bunch of list concatenation functions that do exactly the same thing; concatenate two lists. Actually, they’re all synonyms and so they can all be used interchangeably. There’s also a more general concatenation function that can also be used on lists.
So this article presents five functions that we can use to concatenate lists.
Continue readingIn this article we look at how to automatically enclose values in single quotes when outputting DuckDB query results as a list. Using this method, each value is formatted as SQL literals. This can be useful when you want to escape the values for SQL or for some other purpose.
We also look at how CSV output is sometimes quoted with double quotes, and how we can adjust the results by doing things like removing the headers and changing the list separator.
Continue readingThe generate_subscripts() function in DuckDB creates a series of index values for accessing elements in an array. It can help us iterate through array indices when we need to work with array elements.
Here’s a quick look at DuckDB’s generate_subscripts() function, along with examples.
DuckDB’s command line interface (CLI) provides a convenient .mode csv command that allows you to output all query results directly in CSV format. This approach differs from the COPY statement as it affects the output format of all subsequent queries until changed.
The article takes a quick look at CSV mode in the DuckDB CLI.
Continue readingIn MySQL, list_add() is a system function that adds a value to a comma-separated list of values and returns the result.
So it’s a handy function that allows us to append a value to a list.
Continue readingIn MySQL, list_drop() is a system function that removes a value from a comma-separated list of values and returns the result.
In Redis, we can use the OBECT IDLETIME command to check how many seconds has passed since the last access to a given key.
In Redis, the LTRIM command allows us to trim a list to a specified number of elements. We specify the starting and ending index, which is used to trim the list to just that range.
In Redis, the LSET command allows us to set a list element to a different value, based on its index.